1. Technical Field
The present disclosure relates to the field of semiconductor technology, and more particularly to a semiconductor device and manufacturing method thereof.
2. Description of the Related Art
In the field of semiconductor technology, there is a need to re-design the conventional field effect transistor (FET) device to improve conductivity of the depletion channel while maintaining or reducing threshold voltage variations and junction leakage in the transistor. The improvements resulting from the redesign include lower power consumption and improved device performance, particularly for radio frequency (RF) front-end module devices on a semiconductor chip. The RF front-end module devices typically have more stringent performance and power amplification requirements since they operate at high frequencies (on the order of GHz).
In a conventional field effect transistor, forming an undoped deep depletion channel under the gate is an effective way to increase conductivity of the depletion channel and channel mobility, and is known to those skilled in the art. In addition, forming a threshold voltage control dopant layer beneath the undoped deep depletion channel is also effective in reducing threshold voltage variations. Furthermore, forming a heavily doped region beneath the threshold voltage control dopant layer can also improve bulk grounding or bias.
However, in a conventional semiconductor manufacturing process, after performing ion implantation to form the heavily doped region and threshold voltage control dopant layer in a silicon substrate, a post-doping epitaxial deposition process is typically carried out to form the undoped deep depletion channel under the gate of the FET.
During epitaxial growth of the undoped deep depletion channel, dopants from the heavily doped region and threshold voltage control dopant layer may diffuse into the undoped deep depletion channel. Therefore, to minimize dopant diffusion, the process temperature and duration of the post-doping epitaxial deposition process has to be strictly controlled (to minimize the thermal budget).